← Back to Home

Are Free File Converters Safe? What the FBI Warning Means for You

Published on March 3, 2026

Not all of them. In March 2025, the FBI Denver Field Office warned that criminals were using fake file converter websites to install malware on users' computers. The converters worked as advertised, but the downloaded files contained ransomware, spyware, or credential stealers hidden inside.

What Makes a File Converter Dangerous

The malicious converters identified by the FBI shared a few traits. They required you to upload files to their servers, where your data could be scraped for personal information like Social Security numbers, passwords, and banking details. The converted file you downloaded back could contain embedded malware. Some sites also installed browser hijackers or adware.

The FBI specifically called out tools that convert:

  • DOC to PDF and PDF to DOC
  • Image format converters (JPG, PNG, etc.)
  • MP3 and MP4 downloaders and converters

How to Tell If a File Converter Is Safe

Not sure about the converter you already use? Try our converter safety checker to get an instant risk score. Or check these three things manually:

  1. Does it upload your files? If the site uploads your data to a server, your files pass through infrastructure you do not control. Server-based converters create risk even when the service is legitimate.
  2. Does it require a download? If you need to install software or download an executable, malware can be bundled in. Browser-based tools that run entirely in your tab are safer because there is nothing to install.
  3. Can you verify the processing? Open your browser DevTools (F12) and check the Network tab. If no files are sent to a remote server during conversion, the tool is processing locally.

Browser-Based Converters: The Safer Alternative

Browser-based file converters use JavaScript and WebAssembly to process files entirely on your device. Your files never leave your computer. There is nothing to upload, nothing to intercept, and nothing stored on a server.

FileToolWorks uses this approach for all of its tools. When you compress an audio file, merge PDFs, or remove a background from an image, the conversion runs inside your browser tab using open-source libraries like FFmpeg.wasm and pdf-lib. You can verify this yourself by watching the Network tab in DevTools.

What to Do If You Used a Suspicious Converter

The FBI recommends these steps if you think you used a malicious converter:

  • Run a full antivirus scan immediately. Keep your antivirus software updated.
  • Contact your bank and financial institutions if you converted documents that contained personal information.
  • Change all passwords using a clean, trusted device.
  • Report the incident to the FBI's Internet Crime Complaint Center (IC3) at ic3.gov.

Safe Tools You Can Use Right Now

All FileToolWorks tools process files in your browser with zero server uploads. Here are some of the most popular ones:

For a full explanation of how our client-side processing works, visit our security page. You can also see a side-by-side privacy comparison of 15 popular file converters.